Resistance?

[Isambard Kingdom Brunel]

I have some lights which are powered by 4 AA batteries.

There are 3 lamps in parallel.

I would like to reduce the brightness of the lights and thought if I fitted a resistor in each circuit that would do it.

However I don't know what size I would need.

I also don't know what size the lamps are.

Can anyone advise the best way to do this?

[Dukedog]

Why not just wire the lamps in series?  assuming they are all the same they should burn at approx 1/3rd of the brightness that they would in parallel. 

[SHMD]

Resisters come in, well, many different resistances.

But what you may not now/appreciate is that they also come in many different power ratings.

i.e. How hot they can get – continuously. (This is important.)

 

But the real important issue here is “how often do you want to change the batteries”?

(I can guess the answer here.)

 

 

But you have to help us help you.

We need to know which bulbs you are supplying with the 6volts from the 4 AA batteries.

Are they from bicycle lamps? Grain of wheat bulbs? Lights from old Casio watches (very useful as they are o so small). Etc, etc.

Are there any markings on the bulbs? Where did you get them from?

How much do you want to reduce the brightness by?

 

I would suggest removing one of the AA batteries, from the supply, before putting the bulb(s) in series.

 

 

We can help.

 

 

Kev

 

[cliff park]

A useful point is that bulbs run on a voltage lower than their design value will have a very much extended life. A 6V bulb run from 4V or 5V will have a yellow cast to it, making it look like domestic lighting, and it will last forever.

[Isambard Kingdom Brunel]

Thanks for your help. In cant wire them in series as they are designed to flash independently, In series they would all flash together

They are grain of wheat bulbs.

I cannot see anything on the bulbs.

I wanted to reduce the brightness by about 50%

I like the idea of using only 3 batteries, I will try that tomorrow

[kevinlms]

Thanks for your help. In cant wire them in series as they are designed to flash independently, In series they would all flash together

They are grain of wheat bulbs.

I cannot see anything on the bulbs.

I wanted to reduce the brightness by about 50%

I like the idea of using only 3 batteries, I will try that tomorrow

If they flash independently, is it a commercial/home made circuit board that controls them? If so, perhaps some changes might need to be made there. That could be the resistors within the circuit board, but doing so, might affect the flash rates. Same applies to reducing the number of batteries. Hopefully there is already a series resistor on the output side - that would be a simple solution, i.e. increase those resistors.

 

More information is required.

[Crosland]

When asking questions like this you really need to include ALL the information

 

What's making them flash?

[Isambard Kingdom Brunel]

Just like point out that you can only give ALL the information if you know what information is required.

 

I would like to thank the person that suggested only using 3 batteries.

 

Kev Thanks very much, that has done the job

[Colin_McLeod]

I love this. It's a great example of the engineering maxim that often the best solution the simple one.

[Crosland]

Just like point out that you can only give ALL the information if you know what information is required.

 

I would like to thank the person that suggested only using 3 batteries.

 

 

It should be pretty obvious that the information that the lights are flashing, rather than connected directly to the battery, is significant. Reducing the supply may well not have worked depending on what is doing the flashing.

[kevinlms]

It should be pretty obvious that the information that the lights are flashing, rather than connected directly to the battery, is significant. Reducing the supply may well not have worked depending on what is doing the flashing.

Resistance is futile!